Using Herbicides in Spring-Seeded Alfalfa

Using Herbicides in Spring-Seeded Alfalfa

Weeds can be a major problem in spring-seeded alfalfa.  Roundup Ready alfalfa varieties can help overcome these weeds, but Roundup isn't the only good herbicide option for alfalfa.

Alfalfa seedlings grow slowly.  Many weeds grow faster than alfalfa seedlings, robbing them of moisture, nutrients, and light.  Left uncontrolled, weeds can cause thin stands, weak plants, and lower yields.

Cropping practices that reduce weed seed production during the years prior to planting alfalfa help reduce weeds when you finally do plant alfalfa.  And timely mowing reduces competition from many weeds.  But often the only way to fully control weeds is by using herbicides.

Do you expect grasses like foxtail or crabgrass to be a problem in your new alfalfa?  Then before seeding use a pre-plant incorporated herbicide, like trifluralin, Balan, or Eptam.  These herbicides control grasses and many small-seeded broadleaf weeds like lambsquarter and kochia.  Some larger-seeded broadleaves like velvetleaf and sunflower will not be controlled, but you can mow those weeds later for good control.

Even if you can start the season without any herbicides, they may arrive later. Post-emergence herbicides like Buctril and 2,4-DB control broadleaves; Poast Plus and Select control grasses; and Raptor and Pursuit control a combination of weeds.  They can rescue your alfalfa as long as weeds are sprayed before they get very tall.

Early weed control can help your alfalfa get a good, clean, and fast start.

Always follow label directions for application rates and conditions.

Bruce Anderson
Extension Forage Specialist

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